Over one century the German school system was essentially a half-day school system. But in the last 15 years a great implementation program could raise the quota of all-day-schools in Germany from 15 to 60 percent. This program had especially the following aims: 1) School improvement by enriching the learning culture, 2) reducing diversity and unequal educational chances of students, 3) improving life-work-balance of parents and support for education in families. To fulfill these goals, schools have to create additional learning arrangements like complementary subject-specific courses, exercise courses, support for learning, remedial teaching, projects and work groups and organized leisure time (Holtappels, 2014).

Previous empirical studies in primary schools show that we can expect more effects concerning social behavior than effects in cognitive domains (Holtappels, 2014a):

• National studies in PIRLS 2006 (Holtappels et al., 2010) revealed individual-level analyses and showed that students participating in (any kind of) extracurricular activities in their school have lower achievement levels in reading than half-day students. But this cannot be seen as an all-day school effect because we could ascertain a remedial function of social selective participating of students in extracurricular activities.  
• National studies in PIRLS 2011/TIMSS 2011 (Strietholt et al., 2015; Willems, Wendt & Radisch, 2015) was based on individual-level analyses and propensity score matching and reported that there were no effects of participating in extracurricular activities in all three competence domains and no differences between students from diverse backgrounds.
• The “GO-Study” (Bellin & Tamke, 2010) based on longitudinal data could find a small positive effect depending on  individual participation in extracurricular activities on the development of reading competencies during year 1 and 2, but not compensatory effects for students with migration background.

The paper draw focus on the attendance of students in additional learning time and the process quality of extracurricular learning arrangements and on impacts on the development of students achievement in primary schools. Beyond this the analyses will check whether the gap of different educational chances of students from diverse social background can be reduced. The paper is linked to conference strands because the findings of our study show that a reform of the reform is necessary. German primary schools with all-day schooling should learn more from other European countries with an all-day school system that is effective (for example: Sweden, Netherlands).

The theoretical framework of our study is related to CIPO school quality model with regard to the approach of Scheerens (1990), adapted to the all-day school context through a special school quality model (Holtappels, 2009). The following research questions are leading our analyses that will particularly focus on natural sciences:

1)      Which extracurricular learning arrangements are provided by schools and which level of quality assessed by students can be reported?

2)      Can we find impacts of the student participation in all-day school program and especially in extracurricular domain-specific learning activities on achievement development? Does the quality of extracurricular elements matter?  

3)      How far do students from disadvantaged social backgrounds benefit by participating in extracurricular subject-specific activities?

The results should be ready for transfer and consequences on system level to establish educational standards and preconditions for quality assurance in all-day schooling. At this point the findings of the study can be linked to the European perspective: German federal states that promote all-day schools should seek for orientations on international standards by comparing European countries concerning teaching and learning in school and by shaping a more conducive learning environment. 

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